6 days ago
Field Museum shows 300 million-plus-year-old fossils from Mazon Creek not far from Chicago
Those who know a lot about fossils are likely already familiar with the Mazon Creek fossil just outside Chicago.
Those who don't know a lot about fossils and the Mazon Creek site? They soon will, thanks to the Field Museum of Natural History.
You might remember years ago, the Field Museum had an interactive room called the Place for Wonder, where young kids could touch a taxidermy polar bear and listen to seashells. The Place for Wonder is not around anymore as you may remember it, but today's kids are still full of wide-eyed wonder at the Field Museum — particularly as they learn about the discoveries made at Mazon Creek.
Joseph Goldfarb, 7, has a perfectly appropriate word to express his wonder. He repeatedly said, "Whoa!" as he saw the fossils from Mazon Creek.
But what else can you say when you see something older than the dinosaurs — predating them by something on the order of 130 million years?
Joseph was watching as Dr. Arjan Mann, the assistant curator for fossil fishes and early tetrapods at the Field Museum's Negaunee Integrative Research Center, held up an old, round rock called a concretion.
Inside that rock was a fossil nearly 309 million years old.
"An early amphibian relative called a temnospondyl. It is a new species from Mazon Creek," explained Mann. "If you were to just, you know, even as like an amateur, look at it, you would think that this is a little salamander in the rock."
That temnospondyl is just one of many fossils found not far from home.
"One of the greatest fossil localities in the world, right outside the Chicago area," said Mann.
The Mazon Creek fossil site is less than two hours southwest of Chicago.
The fossils were discovered in piles of rock and dirt left over from coal mining, and have become a treasure trove for fossil hunters.
Mazon Creek is a tributary of the Illinois River. Strictly speaking, sources explain, Mazon Creek itself is one of several localities where fossils have been found called the Francis Creek Shale — with parts located in Grundy, Kankakee, LaSalle, Livingston, and Will counties. But the entire site is commonly called the Mazon Creek area, the Field Museum explained.
Large-scale mining operations began in Mazon Creek in the mid-19th century, and event at that time, it became clear that there was more of interest at the site than coal, the Field Museum explained in a news release.
The fossils at the site are so abundant and so well-preserved that researchers can reconstruct a detailed impression of the prehistoric ecosystem of which they were a part, the museum said.
In addition to the aforementioned relative of the salamander, the fossils also preserve creatures such as squid-like cephalopods, sea scorpions, and a soft-bodied creature with a long snout and primitive eyes called the Tully monster, the Field Museum explained.
"You go about just to every museum collection in the world, you can find Mazon Creek fossils," Mann said. "They're that abundant."
Every spring and summer, amateur fossil hunters at Mazon Creek work alongside professional paleontologists like Dr. Mann and his team.
"I mean, it's one of most fun things you can do, in my opinion, is go fossil collecting and dig in the dirt — and yeah, have fun," said Mann.
Every ancient concretion the paleontologists crack open can teach us something new.
"This is one of the more exciting things because it might be one of the missing links between what we know are modern amphibians like frogs, caecilians and salamanders and their Paleozoic relatives," said Mann. "That's a long paleontological evolutionary mystery."
What else can you say to all that but, "Whoa?"
Dr. Mann and his team have made about a dozen trips to Mazon Creek this summer.
He says that ancient relative of the salamander, the temnospondyl, will be named for the people who found its fossil — a husband and wife who own a rock shop in Evanston.
